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Thermal-Expansion and Fracture Toughness Properties ofParts made from Liquid Crystal Stereolithography Resins
Liquid crystal (LC) resins are a new kind ofstereolithography material that can produce
parts with structured or ordered morphologies instead ofthe amorphous morphologies that result
from standard resins. The LC molecules can be aligned before cure resulting in an anisotropic
crosslinked network when the laser induced polymerization "locks-in" the alignment. Previous
papers have explored liquid crystal orientation dynamics [1], the effects of orientation on viscoelastic and mechanical properties [2,3], and the processing ofLC resins by stereolithography [4].
This paper considers the effects ofmorphology on fracture toughness and thermal-expansion
properties. Both toughness and thermal-stability continue to be important issues for
stereolithography parts. The use ofLC resins may provide a way to significantly improve
performance in both ofthese areas, and in addition result in parts with high upper use .
temperatures.Mechanical Engineerin
Physicians' and nurses' perspectives on increased family reports of pain in dying hospitalized patients
Many indicators suggest that care of the dying in Oregon has been improving over the past decade. However, results from a recent study suggest that one aspect of care of the dying, pain management, may be worsening. In late 1997, family reports of moderate and severe pain in dying hospitalized patients increased from 33% to 57%. This occurred during a volatile time in the Oregon political climate associated with events surrounding a second vote on physician-assisted suicide. In order to better understand the observed increase better, a statewide sample of physicians and nurses was surveyed to obtain their opinions about factors that may have contributed to the increased family reports of moderate and severe pain in dying hospitalized patients. Seventy-nine percent of respondents endorsed two or more factors as partial explanations. These factors include an increase in family expectations about pain management (endorsed by 96%), decreased physician prescribing (endorsed by 66%), and reduced nurse administration of pain medication (endorsed by 59%). Physicians who thought reduced physician prescribing was a partial factor rated fears of the Board of Medical Examiners and the Drug Enforcement Administration as the most likely explanations for decreased prescribing. More research is needed to better understand family expectations for end-of-life care, fears of investigation, and pain medication practices
Detection of HC11N in the Cold Dust Cloud TMC-1
Two consecutive rotational transitions of the long cyanopolyyne HC11N,
J=39-38, and J=38-37, have been detected in the cold dust cloud TMC-1 at the
frequencies expected from recent laboratory measurements by Travers et al.
(1996), and at about the expected intensities. The astronomical lines have a
mean radial velocity of 5.8(1) km/s, in good agreement with the shorter
cyanopolyynes HC7N and HC9N observed in this very sharp-lined source [5.82(5)
and 5.83(5) km/s, respectively]. The column density of HC11N is calculated to
be 2.8x10^(11) cm^(-2). The abundance of the cyanopolyynes decreases smoothly
with length to HC11N, the decrement from one to the next being about 6 for the
longer carbon chains.Comment: plain tex 10 pages plus 3 ps fig file
Characterizing the Initial Phase of Epidemic Growth on some Empirical Networks
A key parameter in models for the spread of infectious diseases is the basic
reproduction number , which is the expected number of secondary cases a
typical infected primary case infects during its infectious period in a large
mostly susceptible population. In order for this quantity to be meaningful, the
initial expected growth of the number of infectious individuals in the
large-population limit should be exponential.
We investigate to what extent this assumption is valid by performing repeated
simulations of epidemics on selected empirical networks, viewing each epidemic
as a random process in discrete time. The initial phase of each epidemic is
analyzed by fitting the number of infected people at each time step to a
generalised growth model, allowing for estimating the shape of the growth. For
reference, similar investigations are done on some elementary graphs such as
integer lattices in different dimensions and configuration model graphs, for
which the early epidemic behaviour is known.
We find that for the empirical networks tested in this paper, exponential
growth characterizes the early stages of the epidemic, except when the network
is restricted by a strong low-dimensional spacial constraint, such as is the
case for the two-dimensional square lattice. However, on finite integer
lattices of sufficiently high dimension, the early development of epidemics
shows exponential growth.Comment: To be included in the conference proceedings for SPAS 2017
(International Conference on Stochastic Processes and Algebraic Structures),
October 4-6, 201
Measles in HIV-infected children in southern Africa
In recent years, southern Africa has experienced a widespread measles outbreak. Given the high human immunodeficiency virus (HIV) prevalence in the region, the particular features of measles in HIV-infected individuals are of interest to clinicians, especially as regards children, as are measles immunisation strategies for this population. This review discusses a case ofsevere measles in an HIV-infected child in Botswana, focusing on its implications for clinical case management in Botswana and similar settings and for policies on measles immunisation
Trends in opioid use over time: 1997 to 1999
Substantial resources have been spent to improve pain control for dying patients, and increased opioid administration has been presumed. Oregon has been a consistent leading state in per capita use for morphine for the past 10 years, as recorded by the Automation of Reports and Consolidated Orders System (ARCOS). Health policy experts, extrapolating from World Health Organization methods, have suggested these data are indicative of the quality of end-of-life care in Oregon. To determine whether trends in opioid prescription at the state and national levels reflect increased opioid use for inpatients during the final week of life, chart reviews were conducted to record all opioid medications administered in the last week of life to 877 adult inpatients who died from natural causes between January 1, 1997 and December 31, 1999. Inpatient morphine use did not increase significantly for dying patients from 1997 to 1999. However, overall morphine use for both Oregon and the United States as measured by ARCOS data increased significantly. Comparisons revealed no significant difference between linear trends for Oregon and U.S. morphine use, but both were significantly greater than the dying inpatients. This pattern was also found for all other opioids. These findings suggest that ARCOS data do not necessarily provide information about opioid use for specific subpopulations of patients and raise questions about the meaning of observed increases in ARCOS data
Integration of Expert Systems and Neural Networks for the Control of Fermentation Processes
Expert systems and neural networks are new tools for the control of fermentation processes. With expert systems the fermentation plant and the process itself is modelled via a generalized, qualitative system description based on the experience of human experts. On the other hand neural networks and interpolating associative memories can learn the process behaviour directly by process observation. The paper at hand reports, how both control techniques can be combined for purposes like process supervision, modelling and optimization of biological plants
Critical Indices as Limits of Control Functions
A variant of self-similar approximation theory is suggested, permitting an
easy and accurate summation of divergent series consisting of only a few terms.
The method is based on a power-law algebraic transformation, whose powers play
the role of control functions governing the fastest convergence of the
renormalized series. A striking relation between the theory of critical
phenomena and optimal control theory is discovered: The critical indices are
found to be directly related to limits of control functions at critical points.
The method is applied to calculating the critical indices for several difficult
problems. The results are in very good agreement with accurate numerical data.Comment: 1 file, 5 pages, RevTe
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